by Gary Strauss, Dan Vergano and Todd Halvorson, USA TODAY

by Gary Strauss, Dan Vergano and Todd Halvorson, USA TODAY

After Friday morning's Russian meteor blast injured 1,100 people, an afternoon flyby of a far bigger asteroid drew plenty of attention for another possible close encounter that buzzed by the Earth at about 2:24 p.m. ET.

While an object half the size of a football field flying at nearly 17,500 mph may be cause for concern in light of the Russian meteor strike, NASA and astronomers from around the globe say the planet and its inhabitants weren't in danger.

The chance of asteroid 2012 DA14 colliding with Earth was infinitesimally small, they say. At its closest, DA14 passed within 17,100 miles of Earth near near Sumatra over the Indian Ocean then headed off into space.

However, if, by chance, it did hit? The fallout would be devastating.

The asteroid would have crashed with the equivalent of 2.4 million tons of dynamite, creating a disaster of regional proportions similar to the 1908 asteroid explosion over Tunguska, Siberia, which flattened 750 square miles of forest.

The Russian meteor, likely about 49 feet wide and travelling at 40,000 miles-per-hour, struck Russia's Chelyabinsk region, about 900 miles east of Moscow at about 9:20 Friday morning, shattering into pieces about 12 to 15 miles above ground. The shock wave damaged 3,000 buildings in Chelyabinsk. Russia said 985 people sought medical care after the shock wave; 48 were hospitalized, mostly because of injuries caused by flying glass.

Scientists see no connection between the two.

"These are two events separated by almost 24 hours, so it is unlikely they are connected," says asteroid expert Richard Binzel of MIT. Meteors the size of the Russian one hit Earth every few years, Binzel says, but hit land near inhabited places much less often. "We just have the incredible coincidence of this happening just before the asteroid flies by," Binzel says.

Unlike the Russian meteor -- whose trail was videotaped as it streaked through the atmosphere -- DA14 wasn't visible with the naked eye. Amateur and professional astronomers in Europe, Africa and Asia will have a chance to see the asteroid with telescopes, though.

The flyby of the asteroid was the closest-ever predicted approach to Earth for an object this large, according to NASA.

NASA reports that DA14's flight trajectory was well distanced from a swarm of low Earth-orbiting satellites, including the International Space Station, but it is inside the belt of satellites in geostationary orbit (about 22,200 miles above Earth's surface.)

Geostationary satellites include dozens of communications satellites and the fleet of weather satellites that keep an eye on storms down here on Earth.

"There is no reason to believe that this asteroid poses a threat to any satellites in Earth orbit," T.S. Kelso, an analyst for Analytical Graphics Inc. and the Space Data Association, told Astronomy Now, a British magazine.